They arrived by horse and buggy, a parade of Old Order Amish, tied together by blood and soil and a shared history of having farmed the countryside around Berne, Ind., for almost 175 years. Many had never been to a doctor before. A few would later faint at the sight of their own blood, as a battery of doctors and nurses from Northwestern Medicine in Chicago set up camp in their community; pricking them with needles, collecting urine samples, capturing images of their hearts and testing the hunch of Dr. Douglas Vaughan, a cardiologist at Northwestern, that the Amish of Berne were the lucky holders of an anti-aging gene.

“In general they don’t avail themselves of modern medicine,” Vaughan says from Chicago. “But they were curious about it.”

The gene is Serpine1, which is responsible for the manufacture of PAI-1 — (a.k.a. plasminogen activator inhibitor) — a protein that regulates blood clotting and forms part of an individual’s “molecular” fingerprint as it relates to aging. Studies in animals have shown that lowering PAI-1 levels can safeguard lab mice against age-related diseases, such as diabetes. But no such study on humans has replicated those results.

Enter Vaughan and his team. They took samples from 177

Amish subjects. Forty-three carried a Serpine1 mutation — and had very low levels of PAI-1. The average life expectancy in the community is 75. But the average life expectancy for those with the mutation — and the lower PAI-1 levels — was 85. Subjects with lower PAI-1 levels also showed better vascular health.

“I had a hunch,” Vaughan says. “I suspected that the carriers of the mutation would have dramatically lower levels of PAI-1.”

The Amish are famously insular, but the Amish of Berne have a long relationship with the scientific community. About 25 years ago, a young girl within the community was discovered with an unusual bleeding disorder. She wasn’t hemophiliac. But when injured she would bleed — stop — and then, a day or two later, start bleeding again. It was found that her blood clotting system worked too well.

Dr. Amy Shapiro, a hematologist at Indiana University, has a long working relationship with the Amish — and their blood. Vaughan called Shapiro and asked her to make some calls on his behalf to the community. The Amish were receptive. Vaughan and his team came to town for two days in May 2015.

“It was a big sacrifice on their part,” he says. “Some of them had never had blood drawn before. We would have these big, strong, Amish men in their 20s, fainting from the needle stick — because they had never had it before.”

The Amish, as a community, were ideal study subjects. They share similar diets, do similar work, and live the same 19th century lifestyles. They also maintain rich genealogical records, so that first cousins from 50 years back, who died at a given age — could be connected to the contemporary generation.

In addition to mutant genes, Vaughan looked at the subjects’ telomeres. Telomeres are the caps on human chromosomes. They shorten as we age and are indicators of our life expectancy — and our likelihood of being felled by, say, a heart attack or cancer or some awful neurodegenerative disease.

Longer telomeres equal longer life. The Amish with the Serpine1 mutation had telomeres that were about 10 per cent longer than those without the mutation.

So have Vaughan and his team — and the Amish — discovered the fountain of youth? Not exactly. What he sees in the gene mutation is an opportunity to develop a drug that could target Type 2 diabetes, insulin resistance and other metabolic complications that either cut a life short or else reduce a person’s ability to enjoy it.

The end goal isn’t to live forever, but to live better.

“The oldest recorded living human being has made it to 122, and I don’t know if we want to go there,” Vaughan says. “What we want to try to do is push back aging-related morbidity. We want to lengthen the health span of people, not necessarily their lifespan.

“You want to live healthier longer — and still be able to enjoy playing golf — or going to a hockey game.”